Document how to run Kuzu with valgrind by setting max db size

[sdht0]

$ valgrind ./build/release/tools/shell/kuzu                                              
==617498== Memcheck, a memory error detector
==617498== Copyright (C) 2002-2024, and GNU GPL'd, by Julian Seward et al.
==617498== Using Valgrind-3.25.1 and LibVEX; rerun with -h for copyright info
==617498== Command: ./build/release/tools/shell/kuzu
==617498== 
Buffer manager exception: Mmap for size 8796093022208 failed.
==617498== 
==617498== HEAP SUMMARY:
==617498==     in use at exit: 0 bytes in 0 blocks
==617498==   total heap usage: 696 allocs, 696 frees, 80,190,707 bytes allocated
==617498== 
==617498== All heap blocks were freed -- no leaks are possible
==617498== 
==617498== For lists of detected and suppressed errors, rerun with: -s
==617498== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

$ valgrind ./build/release/tools/shell/kuzu --max_db_size 8388608                     
==617719== Memcheck, a memory error detector
==617719== Copyright (C) 2002-2024, and GNU GPL'd, by Julian Seward et al.
==617719== Using Valgrind-3.25.1 and LibVEX; rerun with -h for copyright info
==617719== Command: ./build/release/tools/shell/kuzu --max_db_size 8388608
==617719== 
==617719== Warning: set address range perms: large range [0x59cab000, 0x9e9cab000) (defined)
Opening the database under in-memory mode.
Enter ":help" for usage hints.
kuzu> 

[ray6080]

This is a known issue. I think the root cause is that valgrind doesn't work well with mmap. I'm not sure what we should do here. You can either change max_db_size setting or turn on the malloc mode.